The present invention relates to a device for securing the locked position of a motor-vehicle door, especially an outward-swinging door, activated by a post that rotates.
Motor-vehicle doors activated by a rotating post are frequently employed in public transportation in buses, trolleys, and trains. The door is connected to the rotating post by swinging arms and the post can be rotated outwards, with an intermediate screw transmission for example, by a piston-and-cylinder drive mechanism to open and close the door. A mechanism for activating a door of this type is described for example in German Pat. No. 1 961 573.
Positioning a locking device on doors of this type to keep them closed is also known. A locking device of this type is described for example in German Pat. No. 2 062 135. The rotating post in this known device can be rotated axially along with the door panel into the closed position, with locking components on the stationary frame of the door engaging others on the panel.
Since the piston-and-cylinder drive mechanisms of doors of this type are generally operated with compressed air, there is a drawback to the aforesaid known device in that the weight of the door forces the door panel and rotating post to drop when the compressed air fails, releasing the locking device. Unintended unlocking of the door can of course lead to accidents when, for example passengers lean against it from inside.
A device for securing the locked position of a vehicle door activated by a rotating post has accordingly also become known. In this device the door is locked or unlocked by raising and lowering the post and a disk is attached to the post. A rotating support in the form of a double-armed lever is mounted below the disk on a stationary section of the frame. The support can be displaced into a position in which the disk rests on the top of one of the lever arms. A device of this type is described in German Pat. No. 2 805 639 for instance.
The axis on which the support rotates in this known device essentially parallels the longitudinal axis of the rotating post. To release the door, the support is rotated in a plane perpendicular to the length of the post until the disk is released and the post can drop into the unlocking position. To ensure that the door can be opened in an emergency there is a manually operated tension cable that engages the support and can be employed to rotate it into a position in which it is no longer below the disk. Since the weight of the door as a whole rests on the support, it can at times be difficult to displace the support by hand. For this reason, a roller has already been positioned on the support in the known device to facilitate moving the support below the disk.
It turns out that the support in the known device can only be displaced by applying a powerful force, causing problems with respect to unlocking the door in an emergency, which can provoke panic among the passengers under certain conditions.